CHICAGO — Former U.S. Secretary of Education Arne Duncan will not be running for mayor against Lori Lightfoot in the 2023 election, he announced on Tuesday. Duncan, 57, runs Chicago CRED, a nonprofit aimed at violence prevention. Before that, Duncan served as President Barack Obama’s secretary of education and CEO of Chicago Public Schools. He has been considering a run for months but ruled it out Tuesday, saying in a statement, “I am exactly where I need to be, doing the work I love.” In the statement, Duncan said he will “work with anyone serious about making our city safer,” leaving open th…